Tibberaghny Castle, along with its sister fortifications at Ardfinnan and Lismore, served as a defensive line against the powerful kingdoms of Mac Carthaigh in Desmond and Ó Briain in Thomond. These imposing structures represented a clear threat to local Irish rulers, particularly Domhnall Mór Ó Briain, king of Thomond, who viewed them as an encroachment on his traditional lordship.

The tension quickly erupted into violence. On 24 June 1185, Ó Briain’s ‘men of Limerick’ launched an attack on the Tibberaghny garrison. Historical accounts differ slightly in their details; one source records ‘the death of the noble Irishman Oggravus along with many others’, whilst the Annals of Lough Cé specifically name Ruaidhri O’Gradha and Ruaidhri O’Conaing among the Irish casualties, noting they were ‘slain by Foreigners in the slaughter of the castle of Tipraid-Fachtna’. Despite the losses, it appears the Anglo-Norman defenders held their position and emerged victorious from this early confrontation. Curiously, after this dramatic beginning, the castle disappears from historical records entirely.

The physical remains of Tibberaghny Castle were documented by historian Orpen in 1909, who described a motte approximately 30 feet high with a flat, circular summit measuring 18 paces across. The bailey, positioned mainly to the north, followed the natural contours of the rising ground, with traces of a levelled fosse and vallum that likely connected to the motte’s defences at the south-east and south-west corners. Sadly, this medieval monument met an inglorious end when it was levelled in the 1970s, erasing one of the earliest examples of Anglo-Norman military architecture in Ireland.